spacer in front wheel hub

[bigbore2]

I just put on a new front tire and replaced the bearings/seals.  I am not understanding what the spacer is for. It does not seem to do anything , unless it is used a a stop when the axle is tightened.  Who has the skinny on this??

[fj1289]

The inner race prevents side loading the bearing races which will cause the bearings to burn up and sieze in fairly short order. 

[bigbore2]

It prevents bearing side loading because it stiffens up the axle?

[fj1289]

When you tighten the axle nut, the wheel spacer and speedometer gear drive would be putting the squeeze on the inner bearing races.  The inner spacer prevents this from putting the bearings in a bind. 

[Pat Conlon]

                                                              SECTIONAL

|Fork leg|<--spacer-->|inner race|<---------middle spacer------------->|inner race|<--spacer-->|Fork leg|
---------------------------------------- axle------------------------------------------------------------------------
|Fork leg|<--spacer-->|inner race|<--------middle spacer-------------->|inner race|<--spacer-->|Fork leg|

As you tighten the axle nut,  you squeeze the fork legs together (or swing arms) squeezing all 3 spacer tubes (left, center, right) against the left and right side inner bearing races, holding the wheel in correct position.

Just having fun with my key board hoping not to confuse things any worse....

Look at the arrows, that's the load path when you tighten the axle down.

[fj1289]

Nicely done - a bit of a lost art drawing with the keyboard!

[balky1]

                                                             SECTIONAL

|Fork leg|<--spacer-->|inner race|<---------middle spacer------------->|inner race|<--spacer-->|Fork leg|
---------------------------------------- axle------------------------------------------------------------------------
|Fork leg|<--spacer-->|inner race|<--------middle spacer-------------->|inner race|<--spacer-->|Fork leg|

As you tighten the axle nut,  you squeeze the fork legs together (or swing arms) squeezing all 3 spacer tubes (left, center, right) against the left and right side inner bearing races, holding the wheel in correct position.

Just having fun with my key board hoping not to confuse things any worse....

Look at the arrows, that's the load path when you tighten the axle down.

A masterpiece!